Wireless signaling system



July .15, 1924. 1,501,831

E. F. W. ALEXANDERSON WIRELESS IGNALING SYSTEM Ofiginal Filed Jan. 10 1916 Fig. I.

lnventov'. Ernst F.W.A\ex andersor WWW ' His Attorheg Patented July 15, 1924.

UNITED STATES PATENT orrlc'e.

ERNST F. W. ALEXANDERSON, OI SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

WIRELESS SIGNALING SYSTEIVI.

Application filed January 10, 1916, Serial No. 71,190. Renewed August 4, 1921 Serial No. 479,086.

of my prior application, Serial No. 835,433,

filed April 30, 1914. I

It is customary in systems of this description to produce continuous electromagnetic waves of high frequency at the transmitting station and vary either the amplitude or the frequency of these waves in accordance with the sound waves which are to be transmitted. Various means have been proposed for accomplishing the desired result. In order 0 vary the amplitude of the waves transmitted telephone transmitters have been inserted in amplitude of the antenna current has been caused to vary in accordance with variations in the transmitter resistance produced by sound waves. This plan has the disadvantage that all of the antenna current must pass through the telephone transmitter and the amount of power which can be con-.

trolled is therefore limited by the current capacity of the transmitter or transmitters used; In order to vary the frequency of the waves transmitted the inductance of the antenna has been varied by placing in series or in shunt thereto an inductance .device which is varied in accordance with currents produced by sound waves. In most systems of this type however, the current carrying capacity of the transmitters used has been a limiting feature. Y

It has also been roposed to shunt the source of electro-motlve force applied to the antenna by an inductance or resistance and by varying the value of this resistance or inductance vary the effective eleetromotive force acting in the antenna circuit and there by vary the amplitude of the current in the antenna without varying its resistance or inductance.

series with the antenna and in this way the The object of my invention is to overcome the disadvantages which have been I present in previous systems for transmitting signals and provide a system in which the energy which must pass through the telephone transmitter is small in comparison with the total energy supplied to the antenna. A.further object of my invention is to provide a s stem in which the energy radiated from t e antenna varies inversely as the amplitude of the current changes in the telephone transmitter.

In carrying my invention into effect I supply an antenna with high frequency energy and coupleto an inductance in the antenna means for diverting a small portion of the energy from the antenna to an ener consuming device or relay. I vary 1; e amount of energy thus diverted and consumed in accordance with variations in the current in a telephone transmitter. By this arrangement the power factor of the antenna is increased in proportion to the amount of energy diverted and the antenna current is causedto decrease. If the coupling is so designed that the voltage applied .to the energy consuming device or relay is equal to the voltage across the antenna inductance to which it is coupled it may be shown that the ratio between the maximum current in the ener consuming device necessary to reduce t e antenna current to a minimum and the maximum antenna current is equalto the power factor of the antenna current when no energy is be1ng d1- verted therefrom. Assume that: Generator voltage-:E Antenna resistance=R Reactance of system=X Radiation power factor Total power factor=P Total resistancezPX Radiation amperes I= Antenna voltage= g 1-? Assume a voltage transformation ratio: 1 :1

Control currentzi Control wattszei Total watts=I R+ed Total volt ampereszeI Total power factor P Substitute in this equation then PR 'i P T I P El PR i I Substitute in this equation E P TX E1 PR 1X71 E -'L X p for I O t r X when I is maximum E I n Ratio between '11 for I min E E R Radiation I max X R X power factor Since the power factor of the antenna current is usually very low the current which must be carried by the energy consuming device will be small in comparison With the antenna current. If the voltage applied to the energy consuming device is greater than that across the inductance to which it is coupled the current the-rein will be correspondingly less. The energy consuming device or relay which I prefer to employ is of the pliotron or electron discharge type compris- 'ing a cathode provided with means for heating to incandescenc-e, an anode and a current controllin member enclosed in a receptacle which 15 exhausted to such a degree that the passage of current from cathode to anode is not accompanied by any visible manifestation of gas ionization, such as blue glow. with any voltage which may-be aplied thereto. The amount of current flowlng through such a device varies with the potential of the current controlling member and this potential in turn is varied in accordance with variations in the telephone current.

The novel features of my invention are pointed out with particularity in the appended claims. The invention itself however with further objects and advantages will. best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 shows diagrammatically the preferred Way in which my invention may be carried into efi'ect; Figs. 2 and 3 show modi' fications thereof and Fig. 4 shows a modified form of energy consuming device which may be employed in carrying my invention into efiect.

In the form of my invention shown in Fig. 1 the antenna 1 is supplied with high frequency current by means of the alternator 2 which is coupled thereto by the transfornn er 3. The antenna is provided with the usual variable inductance 4 for tuning. An oscillation transformer 5 comprising inductan'ce 6 and condensers 7 so adjusted that it is resonant to the frequency of the antenna has a few of its turns 8 coupled to the in ductance 4. By this means a high voltage is built up across the terminals of condensers 7 but under normal conditions very little energy will be required to maintain this voltage. The voltage across these condensers isapplied to the'anodes 9 and 10 of the energy consuming device or relay 11. The cathode 12 of this relay is provided with a battery 13 for heating it to incandescent-e to cause it to emit electrons and ground connections 14: and -15 are provided between condensers 7 and to the cathode 12. The cathode is surrounded by a grid 16 which is preferably composed of fine Wire wound upon a supporting framework. The potential of this grid is varied in accordance with variations in the current in transformer 17 produced by the telephone transmitter 18 and local battery 19. With relays of this type there is usually a certain definite grid potential at which the greatest sensitiveness of the relay occurs. The value of this potential depends largely upon the design of the particular relay used and may easily be determined by experiment. In order to provide the potential desired a battery 20 of the proper strength and polarity is connected to the grid 16. With this arrangement it will be seen that during one-half cycle there will be a flow of negative electricity from cathode 12 to anode 9, and during the next half cycle there will be a flow from the cathode to anode 10. The battery 20 may be so adjusted that under normal conditions when there is no current in the secondary of transformer 17 there will bebut little cur rent through relay 11, Under these conditions the energy diverted from the antenna greater the telephone current the greater willwill be small and the power factor of the antenna current and also of the current in the oscillation transformer 5 will be very low. When, however, the current in transmitter 18 is varied the potential of grid 16 is varied and when this grid is made more positive the current through relay 11 will increase, the amount of energy absorbed from the oscillation transformer will increase and the power factor of the current in the oscillation circuit will increase. There will be a corresponding increase in the amount of enegry diverted from the antenna and in the power factor of the antenna current. As the power factor of the antenna current increases the effective resistance of the antenna will increase, the current Will decrease and the amount of energy radiated, which variesas the square of the current, will decrease. Thus an increase in the telephone current will produce a corresponding decrease in the antenna current. The rate of increase in the amount of energy diverted however will be much less than the rate of decrease in the amount radiated. The battery 20 is preferably so adjusted that under normal conditions there will be but little current through relay 11.- If then, assuming that the grid is negative, a telephone current is superimposed upon the grid circuit the grid 16 will be made less negative or more positive during the half cycles in which the telephone current opposes the battery current and of course, the

be this change inthe potentialofthe grid. The half cycles of the telephone current during which the potential impressed upon the grid circuit is in the same direction as that of the battery will of course make the grid more negative than normally and will have little effect.

1 Relays of the pliotron type are especially suitable for my pur ose since they are adapted for use with big potentials'and low currents. The oscillation transformer is a convenient means for obtaining the high po.- tential suitable for the operation of the pliotron, but an ordinary air core transformer 21 with a large number of secondary turns loosely coupled to the antenna inductance as shown in Fig. 2 may also be used. In this case the relay 22 Which is indicated has only one anode so'that energy is diverted from the antenna only during every other half cycle of the high frequency current. The power factor of the antenna current however is varied in the same amnner as in the arrangement shown in Fig. 1. In this case'the alternator 2 is shown connected in series with the antenna although it may.

equally well be coupled thereto inductively as in Fig. 1.

In Fig. 3 I have shown another modification which difi'ers from the one shown in Fig. 2 in that the energy diverting means is closely coupled to the tunlng inductance 4. The arrangements shown in Figs. 2 and 3 are useful only when the inductance 4 necessary for tuning forms a substantial portion of the total inductance in the antenna circuit and when this inductance has an effective impedance which is several times greater than the effective resistance of the antenna. On the other hand the form of my invention shown in Fig. 1 is especially suitable when the inductance necessary for tuning the antenna is but a small part of the total inductance. In such a case the inductance 4 may be made much larger than is necessary for tuning but this inductance will in effect he neutralized by the 0011- densers 7 and the final effect in so far as varying the effective resistance of the antenna will be the sameas though the inductance 6 of the oscillation transformer were connected directly in series with the antenna.

In Fig. 4 I have shown a form of electron discharge device which may be substituted for devices 11 and 22 as shown in the other figures and in which there will be a flow of current during every half cycle. This is accomplished by providing two electron emitting cathodes 23 and 24 which are provided with means for heating to incandescence and by interposing between them two grids 25. These grids will preferably be so connected to the secondary of the transformer 26, the primary of which is supplied by the telephone current, that both will be positive at the same time and both will be negative at the same time. It will be evi dent that when an alternating potential is applied to conductors 27 and 28 there will be a flow of current through the device in both directions when the grids are positive and that by varying the potential of the grids the amount of current will be varied accordingly and by this means energy will be diverted from the antenna during "each half cycle instead of during every other/ half cycle as in the forms indicated in Figs, 2 and 3.

By the term effective resistance, as used in the above specification and the claims ,which follow, I mean the electromotive force, in phase with the current at the specified frequency, required to force one ampere of current through thecircuit.

While I have illustrated and described the preferred embodiments of my invention it will of course be understood that various modifications in the precise form of energy consuming means used as well as in the manner of connecting the same to the transmitting system may be made without-departing from the scope of my invention as set forth in the appended claims. v

What I claim as new and desire to secure comprising an electron discharge relay con.-

nected to the antenna for diverting a variable amount of energy from said antenna, and causing the current in the antenna to decrease when the current through the relay increases.

' 3. The combination in a wireless signaling system of an antenna, a source of high frequency alternating current connected thereto for transmitting signals, and means comprising an electron discharge relay connected to the antenna for diverting a variable amount of energy from said antenna, and causing the effective resistance of the antenna to increase when the resistance of the electron discharge relay decreases.

4. The combination in a Wireless signaling system of an antenna, a source of'high frequency alternating current connected thereto for transmitting signals, and means comprising an electron discharge relay for diverting a yariable amount of energy from said antenna and varying the power factor of the current therein, said energy diverting means being so arranged that a small increase in the amount of energy diverted will produce a much larger decrease in the amount of energy radiated.

5. The combination in a wireless signal- 1ng system of an antenna, a source of high frequency alternating current connected thereto for transmitting signals, an oscillation transformer coupled to said antenna and means comprising an electron discharge relay for drawing a variable. amount of energy from said oscillation transformer, and causing the current in the antenna to decrease when the current through the relay increases.

6. The combination in a wireless signaling system. of an antenna, a source of high frequency alternating current connected thereto for transmitting signals, an oscillation transformer coupled to said antenna and means comprising an electron discharge relay for. drawing a variable amount of energy from said oscillation transformer,

and causing the effective resistance ofthe antenna to increase when the resistance of the electron discharge relay decreases.

7. The combination in a wireless signaling system of an antenna, a source of high frequency alternating current connected thereto for transmitting signals, an oscillation transformer coupled to said antenna and means comprising an electron discharge relay for drawing a variable amount of energy from said oscillation transformer and varying the power factor of the current therein, the whole system being so arranged that a small increase in the amount of energy diverted will produce a much larger decrease in the amount of energy radiated.

, 8. The combination in a wireless signaling system of a source of high frequency alternating current, a circuit associated therewith in which inductance is neutralized by capacity through resonance and means comprising an electron discharge relay for diverting a variable amount of energy from said circuit and thereby varying the effective resistance thereof.

9. The combination in a signaling system of a source of high frequency alternating current, a circuit associated therewith in which inductance is neutralized by capacity through resonance, and means connected to said circuit for diverting a variable amount of energy therefrom and varying the effective resistance thereof in direct proportion to the amount of power diverted.

10. Means for transmitting signals comprising a source of high frequency alternating'- current, a resonant circuit associated therewith, an electron discharge relay comprising an electron emitting cathode, an anode and a current controlling member as sociated with said resonant circuit to divert energy therefrom, and means for varying the potential of the current controlling mern. her to vary the effective resistance of the circuit. 11. Means for transmitting signals comprising a source of high frequency alternating current, a resonant circuit associated therewith, a relay comprising electrodes and a current controlling member enclosed in an evacuated envelope, associated with said resonant circuit to divert energy therefrom, and means for varying the potential of the current controlling member to vary the effective resistance of the resonant circuit.

12. The combination in a wireless signaling system, of an antenna, a source of high frequency alternating current connected thereto for transmitting signals, means comprising an electron discharge relay for diverting a variable amount of energy from said antenna and varying the power factor of the current flowing while maintaining substantially constant the elect-romotive force acting on the radiating circuit.

13. The combination in a wireless signal ing system of an antenna, 'asonrce of high frequency alternating --current connected thereto for transmitting signals, an inductance eifectively in series with" the antenna and which represents a substantial portion of the total inductance in the antenna circuit, means comprising an electron discharge relay coupled to said inductance for diverting a variable amount of energy therefrom and varying the power factor of the antenna current while maintaining substantially constant the electromotive force acting on the radiating circuit.

14. The combination in a wireless signaling system of an antenna, a source of high frequency alternating current connected thereto for transmitting signals, an inductance which is effectively in series with the antenna and has an efiective impedance in the antenna circuit which is several times greater than the effective resistance of the antenna, and means comprising an electron discharge relay for diverting a variable amount of energy from said inductance and thereby varying the effective resistance of the antenna and the power factor of the current in the antenna.

15. The combination in a signaling system of a transmitting circuit and means for supplying modulated high frequency oscillations to said transmitting circuit comprising an electron discharge device having an electron emitting cathode and an anode, means for supplying high frequency current to a circuit connected between said cathode and anode, and means for establishing an electric field in the space between cathode and anode which is capable of varying the conductivity of the space between cathode and anode in accordance with low frequency signals.

16. The combination in a signaling system of a transmitting circuit and means for supplying modulated high frequency oscillations to said transmitting circuit comprising.

an electron discharge device having an electron emitting cathode and an anode, means for supplying higlr' frequency current to a circuit connected between said cathode and anode, andmeans for establishing an electric field in the space between cathode and anode which is capable of varying the current flowing between cathode and anode in accordance with low frequency signals.

17 The combination in a signaling system of a transmitting circuit and means for supplying modulated high frequency oscillations to said transmitting circuit comprising an electron discharge device having an electron emitting cathode, an anode and a discharge controlling member, means for supplying high frequency oscillations to a circuit connected between said cathode and anode, and means for varying the potential of the dischar e controlling member in accordance withTow frequency signals.

18. The combination in a signaling system of a transmittin supplying modulate high frequency oscillations to said transmitting circuit compriscircuit and means for ing an electron discharge device having an electron emitting cathode, an anode and a discharge controlling member, means for supplying high frequency oscillations to a circuit connected between said cathode and anode, a circuit between cathode and discharge controlling member, and means for supplying low frequency signaling currents to said circuit.

19. The combination in a signaling system of a transmitting circuit and means for supplying modulated high frequency oscilla tions to said transmitting circuit comprising an electron discharge device having a cathode adapted to be heated to incandescence to enable it to emit electrons, and an anode, means for supplying high frequency current to a circuit connected between said cathode and anode, and means for establishing an electric field in the space between cathode and anode which is capable of varying the conductivity of the space between cathode and anode in accordancewith low frequency signals.

20. The combination in a signaling system of 'a transmitting circuit and means for supplying modulated high frequency oscillations to said transmitting circuit comprising an electron discharge device having a cathode adapted to be heated to incandescence to enable it to emit electrons, and an anode, means for supplying high frequency current to a circuit connected between said cathode and anode, and means for establishin an electric field in the space between cat ode and anode which is capable of varying the current flowing between cathode and anode in accordance with low frequency signals.

21. The method of controlling high frequency current for signaling which consists in impressing a high frequency current upon a transmitting circuit and u on a circuit between the cathode and an e of an electron discharge device, and producing in the space between the cathode and anode an electric field which isrcapable of varying the conductivity of the space between cathode and anode in accordance with variations in a low frequency signaling current.

22. The method of controlling high frequency current for signaling which consists in impressing a high frequency current upon a transmitting circuit and upon a circuit between the cathode and anode of an electron discharge device, and producing in the space 23. The method of controlling high frequency current for transmitting currents produced by sound waves which consists 1n impressing a high frequency current upon a transmitting circuit and upon a circuit between the cathode and anode of an electron discharge device, and producing in the space between cathode and anode an electric field which is capable of varying the conductivity of the space between cathode and anode in accordance with variations in the currents to be transmitted.

24. The method of controlling high frequency current for signaling which consists in impressing a high frequency current upon a transmitting circuit and upon a circuit between the cathode and anode of an electron discharge device having an electron emitting cathode, an anode and a discharge controlling member, and varying the conductivity of the space between cathode and anode by varying the potential of the discharge controlling member in accordance with low frequency signals.

25. The combination in. a high frequency signaling system of a transmitting circuit, a source of high frequency alternating current connected to said transmitting circuit, means for diverting a portion of the energy of said source from said circuit comprising an electron discharge device having an electron emitting cathode, an anode and a discharge controlling member and having its cathode and anode associated with said circuit, and means for varying the potential of said discharge controlling member in accordance with signals.

26. The method of signaling which consists in impressing a source of high frequency alternating current upon a transmitting circuit and upon the cathode and anode of a relay device having an electron emitting cathode, an anode and a current controlling member, and diverting a variable amount of energy of said source through said relay de vice by varying the potential of the current controlling member.

27. The combination in a wireless signaling system of an antenna, a relay having an electron emitting cathode, an anode, and a current controlling member, a source of high frequency electrical pulsations connected to said antenna and to the cathode and anode of said relay, and means for varying the potential of said current controlling member in such a way as to vary the electrostatic field in said relay in accordance with the signals to be transmitted, and thereby produce corresponding variations in the conductivity of said relay.

28. The combination in a wireless signaling system of an antenna, a relay having an anode and a cathode capable of emitting electrons independently of the current passing through the relay, a-source of high frequency electrical pulsations connected to said antenna and to the cathode and. anode of said relay, and means for varying the electrostatic field in said relay in accordance with the signals to be transmitted.

29. The combination in a wireless signaling system of an antenna, a relay device comprising an electron emitting cathode and an anode enclosed in an evacuated receptacle and capable of operation substantially independent of gas conductivity, a source of high frequency energy connected to said antenna and to said relay device and means for varying the conductivity of said relay device to vary the amplitude of the current waves in said antenna.

50. The combination in a wireless signals ing system of an antenna, a relay device having unidirectional conductivity and corn prising an electron emitting cathode, an anode and a grid shaped member interposed between said cathode and anode, a source of high frequency energy connected to said antenna and to the cathode and anode of said relay device, and means for varying the potential of the grid shaped member to vary the conductivity of said relay device.

31. In a system for signaling by high frequency oscillations, a thermionic device of the audion type for modulating high frequency oscillations in accordance with low frequency signals, said device having an input and an output circuit, said input circuit comprising a heated filament and a control.- ling electrode, means for generating low frequency signals, and means for impressing said low frequency signals upon the input circuit of said device.

32. In a system for signaling by high frequency oscillations, a thermionic device for modulating said high frequency oscillations in accordance with low frequency signals, said. device comprising an evacuated vessel containing a filament, an auxiliary electrode and a plate element, and means for changing the potential of the auxiliary electrode with respect to the filament in accordance with low frequency signals to be transmitted.

33. In a system for signaling by high frequency oscillations, a thermionicdevice for modulating said high fr uency oscillations in accordance with low said device comprising an evacuated vessel containing a filament, an auxiliary electrode and a plate element, means for generating low frequency signals, and means for impressing said signals between the filament and the auxiliary electrode.

34. A signaling system comprising an au-- dion having filament, grid and plate electrodes, means for supplying high frequency oscillations to said audion, signaling means associated with said audion, and a circuit connected to said plate and said filament electrodes for leading off from said audion. high frequency oscillations modulated in acoordance with said signal.

requency signals, l

35. A signaling system comprising an audion having filament, grid and plate electrodes, means for supplying high frequency oscillations, means for supplying signaling oscillations, means comprising said audion for modulating said high frequency oscillations in accordance with said signaling oscillations, and a circuit connected to said filament and plate electrodes for leading off the modulated oscillations from said audion.

36. In a wireless signaling system, a source of high frequency oscillating current, a radiating antenna system associated therewith and an auxiliary circuit operatively connected to said antenna system and supplied with energy therefrom, said auxiliary circuit including the cathode and anode of an electron discharge relay having an incandescent cathode, an anode and a grid enclosed in an evacuated receptacle, and means for controlling the current in said auxiliary circuit.

37. In a wireless signaling system, a source of high frequency oscillating current, a radiating antenna system ascociated therewith and an auxiliary circuit operatively connected to said antenna system and supplied with energy therefrom, said auxiliary circuit including the cathode and anode of an electron discharge relay having an incandescent cathode, an anode and a grid enclosed in an evacuated receptacle and sound actuated means for controlling the current in said auxiliary circuit.

38. In a wireless signaling system, a source of high frequency oscillating current,

a radiating antenna system associated therewith and an auxiliary circuit operatively connected to said antenna system and supplied with energy therefrom, said auxiliary circuit including the cathode and anode of an electron discharge relay having an incandescent cathode, an anode and a grid enclosed in an evacuated receptacle, and means for varying the current through said relay and thereby varying the amplitude of the current in the antenna.

In witness whereof, I have hereunto set, 

